I don't know the current population of L.A. city (it's not 10 million), or how many of the people eligible to vote in L.A. are registered, but this is from the last mayoral race in 2001
June 8, 2001 - Of the 1,538,229 registered voters in the City of Los Angeles, 556,979--or 36.21%--showed up at the polls to vote.
http://www.csun.edu/~govrel/ArchivesJan-June01.html
thanks DD, I saw that just tonite..36% is not a lot. very sad.